Characteristics and predicted outcome of patients lost to follow-up after degenerative lumbar spine surgery.

PURPOSE: The relatively large number of participants lost to follow-up (attrition) in spinal registers calls for studies that investigate the features of these individuals and their possible outcome. The aim was to explore the effect of attrition on patient-reported outcome in patients undergoing degenerative lumbar spine surgery. Three groups were studied: spinal stenosis (LSS), disc herniation (LDH) and degenerative disc disorder (DDD). METHODS: Patients who underwent surgery for degenerative lumbar spine conditions during 2008-2012 according to registration in the Swespine national register were eligible for the study. Non-respondents were registered in Swespine prior to surgery, but not at follow-up. Swespine data were merged with hospital data from seven Swedish regions (65% of the population), Statistics Sweden, the National Patient Register and the Social Insurance Agency. Baseline characteristics of non-respondents were described and compared to those of the respondents. Coefficients from regression analyses on PROM values for respondents were used to estimate the levels of PROM values for non-respondents, assuming the same effects of baseline characteristics for the two subgroups. Regression analyses were then conducted to identify variables associated with non-response. The results from the regression analyses were used to predict outcomes for patients with the characteristics of a non-respondent. Primary outcome variable in LSS and LDH was Global Assessment for leg pain, and in DDD, Global Assessment for back pain. RESULTS: Age, sex, educational level, smoking, living alone, being born outside the EU, previous spine surgery and unexpected events before follow-up were factors that were significantly associated with non-response. Being born inside, the EU was important in all of the studied groups (LSS: OR 0.61 p = < 0.000; LDH: OR 0.68 p = 0.001; DDD: OR 0.58 p = 0.04). For spinal stenosis patients, an unexpected event appeared particularly important (OR 3.40, p = 0.000). The predicted outcome of non-respondents was significantly worse than for respondents (LSS: 75.4% successful outcome vs. 78.7%; LDH: 53.9% vs. 58.2%; DDD: 62.7% vs. 67.5%. P-value in all groups = < 0.000). CONCLUSION: Attrition in Swespine cannot be ignored, as non-respondents were predicted to have worse outcome. The effect of attrition bias should always be considered when contemplating outcome recorded in a quality register with patients lost to follow-up.

ISSLS prize in clinical science 2020: the reliability and interpretability of score change in lumbar spine research.

PURPOSE: A statistically significant score change of a PROM (Patient-Reported Outcome Measure) can be questioned if it does not exceed the clinically Minimal Important Change (MIC) or the SDC (Smallest Detectable Change) of the particular measure. The aim of the study was to define the SDC of three common PROMs in degenerative lumbar spine surgery: Numeric Rating Scale (NRSBACK/LEG), Oswestry Disability Index (ODI) and Euroqol-5-Dimensions (EQ-5DINDEX) and to compare them to their MICs. The transition questions Global Assessment (GABACK/LEG) were also explored. METHODS: Reliability analyses were performed on a test-retest population of 182 symptomatically stable patients, with similar characteristics as the Swespine registry population, who underwent surgery for degenerative lumbar spine conditions 2017-2018. The MIC values were based on the entire registry (n = 98,732) using the ROC curve method. The ICC for absolute agreement was calculated in a two-way random-effects single measures model. For categorical variables, weighted kappa and exact agreement were computed. RESULTS: For the NRS, the SDC exceeded the MIC (NRSBACK:3.6 and 2.7; NRSLEG: 3.7 and 3.2, respectively), while they were of an equal size of 18 for the ODI. The gap between the two estimates was remarkable in the EQ-5DINDEX, where SDC was 0.49 and MIC was 0.10. The GABACK/LEG showed an excellent agreement between the test and the retest occasion. CONCLUSION: For the tested PROM scores, the changes must be considerable in order to distinguish a true change from random error in degenerative lumbar spine surgery research. These slides can be retrieved under Electronic Supplementary Material.

Follow-up of degenerative lumbar spine surgery-PROMs stabilize after 1 year: an equivalence study based on Swespine data.

PURPOSE: To evaluate the outcome of degenerative lumbar spine surgery in a credible way, patient-reported outcome measures (PROMs) should be assessed after an adequate follow-up period. Most authors/journals consider a follow-up period of less than two years to be too short. The purpose of this study was to explore the possibility of restricting follow-up to one year. METHODS: Adult patients operated between 1998 and 2017 were retrieved from Swespine (Lumbar Disc Herniation n = 31,314, Lumbar Spinal Stenosis n = 53,043 and Degenerative Disc Disease n = 14,375). The proportion reaching the minimal important change (MIC) in Visual Analogue Scale for pain (VASBACK/LEG), Oswestry Disability Index (ODI) and the quality-of-life measure EQ-5DINDEX at 1 and 2 years, respectively, was calculated. The single-item questions such as Global Assessment (GABACK/LEG) and Satisfaction were analysed by the McNemar test. Threshold values for a successful outcome based on the final scores of each PROM at 1 and 2 years post-surgery were also defined. RESULTS: For all the three diagnostic groups, the differences in proportions reaching MIC of each PROM at 1 and 2 years were below 2%. Global Assessment and Satisfaction with outcome at one year remained at 2 years. There were no important differences of threshold values of treatment success based on final scores CONCLUSION: No clinically important changes in PROMs appeared between 1 and 2 years after surgery for degenerative lumbar conditions, demonstrating that a follow-up period of 1 year as opposed to 2 years is sufficient in effectiveness studies if PROMs are to be used as outcome variables. These slides can be retrieved under Electronic Supplementary Material.

The value of patient global assessment in lumbar spine surgery: an evaluation based on more than 90,000 patients.

PURPOSE: There are two, principally different ways to obtain patient opinions regarding the outcome of spine surgery: using prospective multi-item questionnaires preoperatively and at follow-up, and using a retrospective single-item question at follow-up-both methods have distinct advantages and limitations. The purpose of the study was to explore the utility of using the simple transition question global assessment, GA, ("How is your back/leg pain today as compared to before the surgery?") as an overall patient-reported outcome measure (PROM) based on the large real-life database in the Swedish spine registry (Swespine). METHODS: The correlation between GA and the score-changes and the final scores at 1 year of follow-up for the PROMs VAS, ODI, and EQ-5D was examined. The correlations between GA and item-specific domains within the ODI, EQ-5D and SF-36 as well as the discriminative ability of PROMs with GA as reference criterion were also analysed. The cohort consisted of 94,132 patients registered in Swespine who were surgically treated for disc herniation, spinal stenosis or degenerative disc disease. RESULTS: The correlation coefficients for GA vs. the score-changes were lower than for GA vs final scores. For VAS they ranged for the different diagnosis groups from 0.33 to 0.61 and from 0.50 to 0.79, respectively. For ODI, the corresponding values ranged from 0.43 to 0.65 and 0.63 to 0.76; for the EQ-5D from 0.32 to 0.45 and 0.54 to 0.71. Further, GA showed a somewhat stronger correlation to pain-specific PROMs than to quality-of-life PROMs. CONCLUSIONS: The single-item outcome measure global assessment (GA) appears to be a feasible overall patient-reported outcome measure (PROM) and a useful reference for interpreting the scores of patient-reported outcome measures.

Pain-drawing does not predict the outcome of fusion surgery for chronic low-back pain: a report from the Swedish Lumbar Spine Study.

Despite a widespread use of pain drawing in the selection of patients for surgical and non-surgical treatment, its value as a predictor of outcome is still not well documented. In a prospective multicentre randomised controlled trial of surgical and non-surgical treatment for chronic low-back pain (CLBP), two hypotheses were tested: (1). Pain drawing predicts outcome of treatment for CLBP, (2). Pain drawing is associated with psychological characteristics of patients with CLBP. Two hundred and sixty-four patients with severe CLBP of long duration completed pain drawings as part of a battery of questionnaires prior to treatment. They were followed up at 2 years post-treatment, with renewed completion of questionnaires. Outcome was measured in three ways: patient global assessment, change of disability/pain, and work status. The pain drawing was analysed by four different methods. The association between the pain drawings and outcomes was analysed. Personality traits and depressive symptoms were evaluated in the psychological assessment. None of the four methods of interpretation of the pain drawings demonstrated any significant association with outcome, in either the surgical or the non-surgical group. The pain drawing was associated with pre-treatment back pain intensity and depressive symptoms. No predictive value of the pain drawing regarding the outcome of treatment of CLPB was demonstrated. The concept of "organic/non-organic" pain in conjunction with chronic low-back pain is not supported by the results of the present study.

The clinical importance of changes in outcome scores after treatment for chronic low back pain.

When measuring treatment effect in chronic low back pain with multi-item outcome instruments, it is necessary, both for clinical decision-making and research purposes, to understand the clinical importance of the outcome scores. The aims of the present study were three-fold. Firstly, it aimed to estimate the minimal clinically important difference of three multi-item outcome instruments (the Oswestry Disability Index, the General Function Score and the Zung Depression Scale) and of the visual analogue scale (VAS) of back pain. Secondly, it aimed to estimate the error of measurement of these instruments; and its third aim was to describe the clinical meaning of score change. The study population consisted of 289 patients treated surgically or non-surgically in a randomised controlled trial. The minimal clinically important difference was estimated with patient global assessment as the external criterion. It was compared with the standard error of measurement of the instruments. The individual items of the instruments were compared for score changes related to improvement and deterioration. The standard error of measurement of the Oswestry Disability Index, the General Function Score and the Zung Depression Scale was 4, 6 and 3 units, respectively. The 95% tolerance interval was 10, 16 and 8 units, respectively. The minimal clinically important difference was 10, 12 and 8-9 units, respectively, thus not significantly exceeding the tolerance interval. The minimal clinically important difference of VAS back pain was 18-19 units, well exceeding the 95% tolerance interval, which was 15 units. Improvement after treatment for chronic low back pain tends to occur to a greater extent in sleep disturbance, ability to do usual things and psychological irritability, but to a lesser extent in the ability to sit, stand and lift. We conclude that the VAS of back pain is responsive enough to detect the minimal clinically important difference, whereas the smallest acceptable score changes of the Oswestry Disability Index, the General Function Score and the Zung Depression Scale may require an increase to exceed the 95% tolerance interval when used for clinical decision making and for power calculation. Despite improvement after treatment, the ability to sit, stand and lift, remain notable problems.

Predictors of outcome in fusion surgery for chronic low back pain. A report from the Swedish Lumbar Spine Study.

Despite the continuous development of surgical techniques and implants, a substantial number of patients still undergo surgery for chronic low back pain (CLBP) without any benefit, or even become worse. With the aim of finding predictors of functional and work status outcome, 264 patients with severe CLBP of long duration, randomised to surgical or non-surgical treatment, were characterized by socio-demographic, clinical, radiological and psychological variables. The variables were estimated as predictors of outcome at the 2-year follow-up. Univariate and multiple logistic regression analyses were used in both treatment groups. We found that a personality characterized by low neuroticism and low disc height were significant predictors of functional improvement after surgical treatment. Depressive symptoms predicted functional improvement after non-surgical treatment. Work resumption was predicted by low age and short sick leave in the surgical group, and by short sick leave in the non-surgical group. We conclude that improved selection of successful surgical candidates with CLBP seems to be promoted by attention to severe disc degeneration, evaluation of personality traits and shortening of preoperative sick leave.

2001 Volvo Award Winner in Clinical Studies: Lumbar fusion versus nonsurgical treatment for chronic low back pain: a multicenter randomized controlled trial from the Swedish Lumbar Spine Study Group.

STUDY DESIGN: A randomized controlled multicenter study with a 2-year follow-up by an independent observer. OBJECTIVES: To determine whether fusion of the lower lumbar spine could reduce pain and diminish disability more effectively when compared with nonsurgical treatment in patients with severe chronic low back pain (CLBP). SUMMARY OF BACKGROUND DATA: The reported results after fusion surgery on patients with CLBP vary considerably, and the evidence of treatment efficacy is weak in the absence of randomized controlled studies. PATIENTS AND METHODS: A total of 294 patients referred to 19 spinal centers from 1992 through 1998 were randomized blindly into four treatment groups. Patients aged 25-65 years with CLBP for at least 2 years and with radiologic evidence of disc degeneration at L4-L5, L5-S1, or both were eligible to participate in the study. The surgical group (n=222) included three different fusion techniques, not analyzed separately in this study. Patients in the nonsurgical group (n=72) were treated with different kinds of physical therapy. The surgical group comprised 49.5% men, and the mean age was 43 years. The corresponding figures for the nonsurgical group were 48.6% and 44 years. The patients had suffered from low back pain for a mean of 7.8 and 8.5 years and been on sick leave due to back pain for a mean of 3.2 and 2.9 years, respectively. The Visual Analogue Scale (VAS) was used to measure pain. The Oswestry Low Back Pain Questionnaire, the Million Score and the General Function Score (GFS) were used to measure disability. The Zung Depression Scale was used to measure depressive symptoms. The overall result was assessed by the patient and by an independent observer. Records from the Swedish Social Insurance were used to evaluate work disability. Patients who changed groups were included in the analyses of significance according to the intention-to-treat principle. RESULTS: At the 2-year follow-up 289 of 294 (98%) patients, including 25 who had changed groups, were examined. Back pain was reduced in the surgical group by 33% (64 to 43), compared with 7% (63 to 58) in the nonsurgical group (P=0.0002). Pain improved most during the first 6 months and then gradually deteriorated. Disability according to Oswestry was reduced by 25% (47 to 36) compared with 6% (48 to 46) among nonsurgical patients (P=0.015), according to Million by 28% (64 to 46) compared with 8% (66 to 60) (P=0.004), and accordingtoGFS by 31% (49 to 34) compared with 4% (48 to 46) (P=0.005). The depressive symptoms, according to Zung, were reduced by 20% (39 to 31) in the surgical group compared with 7% (39 to 36) in the nonsurgical group (P=0.123). In the surgical group 63% (122/195) rated themselves as "much better" or "better" compared with 29% (18/62) in the nonsurgical group (P<0.0001). The "net back to work rate" was significantly in favor of surgical treatment, or 36% vs. 13% (P=0.002). The early complication rate in the surgical group was 17%. CONCLUSION: Lumbar fusion in a well-informed and selected group of patients with severe CLBP can diminish pain and decrease disability more efficiently than commonly used nonsurgical treatment.

The General Function Score: a useful tool for measurement of physical disability. Validity and reliability.

The General Function Score (GFS) is a disease-specific instrument consisting of nine items focusing on strict physical activities of daily living. It is intended as an alternative to the more complex scores of disability (such as the Oswestry Disability Index), serving as a complement to the quality of life instruments in the study of low back pain (LBP). It was developed from an original 17-item questionnaire, of which 11 of the items were tested for criterion validity in an observer-supervised performance test. Two items were excluded from further analysis because of too low a validity. The remaining nine-item GFS was tested for construct validity, reliability, feasibility and responsiveness in six different cohorts: 297 patients with chronic low back pain (cohort 1), an age- and sex-matched control group of 287 randomly allocated Swedish citizens (cohort 2), three separate groups of patients admitted for surgery due to low back disorders (cohorts 3-5) and outpatients with spinal disorders (cohort 6). Correlations were tested with the Spearman Rank correlation coefficient, differences between groups with the Mann-Whitney test and the internal consistency with the Cronbach's coefficient alpha. The GFS total scores showed correlations of 0.78, 0.81 and 0.88 in the three aspects of the performance test. The response rate was 98.3-100%. The mean time to complete the questionnaire was 1.2 min. The internal consistency was 0.69 and 0.86 in cohorts 1 and 2 respectively. The test-retest correlation was 0.88. The GFS showed a high responsiveness to difference and change. The effect size was 0.82-0.96 in surgically treated disc herniation and 0.55-0.85 in spondylolisthesis. The GFS is a highly valid and reliable instrument with good responsiveness and feasibility, useful for evaluation of physical disability.

Facet joint asymmetry and protrusion of the intervertebral disc.

In a study of 47 cases of lumbar disc protrusion, the hypothesis that asymmetry of the facet joints is correlated with the presence of a disc protrusion, was tested. Seventeen cases of protrusion of the L4-L5 disc and 30 cases of protrusion of the L5-S1 disc were measured on coronal computed tomography (CT) scans. The nonprotruded discs of each level were used as controls of the protruded discs of the same level. The transverse interfacet angle, the inclination and curvature of the facet joints, and the frequency of asymmetric facet joints showed no significant differences, whether there was a disc protrusion or not. The magnitude of the asymmetry was significantly greater only at the L4-L5 interspace in cases of disc protrusion. However, taking into consideration the error of measurement, the difference becomes highly questionable. These results do not indicate any relation between facet joint asymmetry and protrusion of the intervertebral disc.

Acromioplasty for impingement syndrome.

In 51 patients (27-67 years) with subacromial impingement syndrome, an acromioplasty according to Neer was performed. In 11 patients, acromioclavicular arthrosis was found, and in these patients the lateral end of the clavicle was resected as well. The patients have been followed for an average of 21 (6-42) months. The result was excellent or good in 33 patients. In seven patients there was no improvement.

Doxycycline prophylaxis in fracture surgery.

Doxycycline was given as preventive preoperative treatment to 64 patients with fractured collum femoris. 46 patients, not administered doxycycline, served as controls. The overall incidence of postoperative infection was 6.3 and 6.5% in treated and control groups respectively. It is concluded that doxycycline preventive treatment offers no advantage in this type of operative procedure.

Doxycycline concentration levels in bone, soft tissue and serum after intravenous infusion of doxycycline. A clinical study.

As part of a longitudinal study, the influence of preoperative single dose doxycycline treatment on the overall incidence of early postoperative wound infections in orthopaedic surgery, 34 patients with various fractures were given an intravenous infusion of doxycycline 2-4 hours before the operation. The serum concentrations of doxycycline were determined on specimens taken during the operation and on 4 other occasions, the last being 48 hours after operation. All patients except 4 had serum concentration levels of 0.4 mug per ml or above at 48 hours. During the operation, specimens of skin, subcutaneous tissue, muscle and bone were also taken. The doxycycline concentrations were determined in the various tissues and correlated to the concomitant serum concentration. The results were analysed with regard to the possible influence of preoperative single dose doxycycline treatment for prevention of early postoperative infections.